Accurate measurement of angles is important in a variety of fields including for example the manufacturing industries such as the automotive field. Measurement of such angles is also critical and difficult when being limited in confined spaces.
For example, proper alignment of wheels of an automotive vehicle is important for both proper handling of the vehicle, as well as proper tire wear. One of the wheel alignment parameters, which is measured and adjusted in order to achieve proper wheel alignment, is the caster angle.
Caster is an angle which the steering axis of a steerable wheel makes with respect to a vertical plane which is perpendicular to the longitudinal direction of the vehicles. The caster angle is considered positive when the steering axis is inclined rearward (in the upward direction) and negative when the steering axis is inclined forward. Caster can be measured by inclinometers attached to the wheel. To measure caster, the wheel is turned through an arc, and the difference in camber readings is used to derive the caster value. The camber angle is the inclination of the wheel plane with respect to the vertical. The camber angle is another parameter that is used for wheel alignment along with the caster angle.
Current wheel alignment tools are not able to accurately measure the caster angle in a convenient, efficient and accurate manner. Current angle measurement tools are large and the reading of measurements is difficult when measuring the angles due to low clearance or inaccessibility. For example, current angle gauges will not fit in confined spaces where the rear casters of the vehicles are located. Further, the current equipment is unable to include a remote display of the angle that is required when measuring in an inaccessible space, while displaying the measurement in a convenient and efficient manner.
Other wheel alignment tools can be placed underneath the car to take measurements of the angles. However, even laser range finders cannot get an accurate measurement.
In some recent models of vehicles, such as the 2006 versions of the PONTIAC SOLSTICE and SATURN SKY from GENERAL MOTORS, Inc., the vehicles have adjustable rear casters. In an effort to achieve mass reductions, GENERAL MOTORS made the decision to have a body rear structure that eliminated the rear frame. There is a need to measure the adjustable rear casters. However, the confined space available for the measurement of the caster angle and the size of the current tools make it very difficult to measure the angles. Thus the conventional tools cannot be used to measure angles, such as the caster angle of certain vehicles.
Accordingly, it is desirable to provide a technique and apparatus for measuring angles in confined spaces while still being able to display the measurement in a convenient manner for the user.